People benefit from plastic articles. From their invention in the mid-20th Century until the present, thermoplastic polymers have become the composition of many consumer products. Such products are relatively lightweight, sturdy, and corrosion resistant.
Thermoplastic polymers during the past half-century have used resins produced from petrochemical feedstocks. As this Century progresses, there will be an increasing need to produce thermoplastic polymers from biomass feedstocks, whether because of geopolitical considerations, environmental considerations, or supply considerations. One of the thermoplastic polymers produced from bio-derived sources are polyhydroxyalkanoates.
According to European Patent Publication 1 705 250, polyhydroxyalkanoates (PHAs) are biological polyesters accumulated in cells by special microorganisms under special growth conditions and have the following general formula:
in which, n and m are integers from 1 to 4; R1 and R2 are straight chain or branched chain C1-12 alkyl which are substituted or non-substituted; X and Y are not 0 simultaneously, and determine the content of the components in copolymer. The average molecular weight of PHAs is generally 1-4 million Da.
The physical property of PHAs is similar to that of polypropylene. But because its biodegradability, biocompatibility, piezoelectricity and optical activity are characteristics not possessed by common petrochemical resins, it has wide application prospect in industry, agriculture, medicine, sanitation, food, electronics, etc.
Unfortunately, PHAs are quite brittle without modification by additives.